Wednesday, July 21, 2010

Setup Kettle debugging in 2 minutes

Sometimes it could be very interesting to be able to debug something to understand better how it works from an internal standpoint. My experience says that this is the case with the majority the opensource projects: sooner or later this is will happen.

Today that happened with Kettle trying to better understand if my assumptions were correct.

So how can we easily debug Kettle? The answer is very easy is: use remote debugging. I'll explain everything in a minute. The development tool I'm using is IntelliJ IDEA but it is fairly simple to set up everything with Eclipse and Netbeans.

Setup Kettle to enable remote debugging

1) If you're on Windows, open Spoon.bat and add the following line

set JAVA_OPTS=-Xdebug -Xrunjdwp:transport=dt_socket,address=8000,server=y,suspend=n

1) Configure a project for Kettle source tree
2) Choose Build > Edit configurations from the menu
3) The Run/Debug Configurations dialog opens. Choose Add New Configuration (the + sign in the upper left corner) and select Remote from the Add New Configuration list

3) The Remote Configuration dialog opens

Configure Transport and Debugger mode choices as displayed in the image above. The set the Host address (localhost in this case or wherever you need) and the port (8000 in my case) and press Ok

And now let's dance...

So now start Kettle. As soon as Kettle started load you job or transformation and, before running it, launch the debugger from your IDE. As soon as the debugger started you're ready to launch your job/transformation and begin your investigation. The advantage of this approach is the ability to debug also remotely running kettle instances and that is useful sometimes in helping to investigate problems.